Hammermill screen



Feb 23, 1965 w. F. KoL-rs ETAI. 3,170,640

HAMMERMILL SCREEN Filed June 4, 1963 United States Patent O 3,170,640 HAMMERMILL SCREEN William F. Kolts and Robert J. Reese, Carmel, Ind., assignors to Economy Elevator Enterprises, Inc., Carmel, Ind., a corporation of Indiana Filed June 4, 1963, Ser. No. 285,503 1 Claim. (Cl. 241-86) This yinvention relates to a screen for hammerlnills, and has for its object the provision of a screen which can be used in different forms of conventional hammermills, which will provide a control for the distance between the mill rotor and the perforated screen section, which will provide such control without any substantial reduction in the area of said perforated section, and which can be economically manufactured from inexpensive sheet-metal.

According to one form of our invention, there is provided an arcuate Vscreen having a centrally disposed perforated section. Said perforated section is rigidly interconnected at its outer edges to a border which projects longitudinally and laterally outwardly from said perforated section for reception in locating supports in a conventional hammermill base for mounting the screen thereon. The perforated section and border lie in parailel offset planes for thus disposing said perforated section at a controlled distance from the rotors of the hammermill in which the screen is mounted.

Other objects and features of our invention will become apparent from the more detailed description which follows and from the accompanying drawing, in which:

FIG. 1 is a vertical Section of a mill having a screen embodying our invention mounted therein;

FIG. 2 is an isometric view of the screen shown in FIG. 1;

FIG. 3 is a plan view View of the screen shown in FIG. 1; and

FIG. 4 is a vertical section taken on the line 4-4 of FIG. 3.

Our screen is adapted to be used in a conventional hammermill which, as shown in FIG. 1, may comprise an upper semi-cylindrical housing provided with an inlet 12 and connected, as by bolts 14, to a lower semicylindrical housing 16 provided with an outlet duct 1S. A rotor 20 provided with a plurality of radially projecting heads 21 is carried within the mill housing 10 and 16 on a drive shaft 22. The opposed side walls of the lower housing 16 of the hammermill shown have'semicircular grooves 24 formed therein for the reception of a screen which acts in combination with the rotor heads 21 for grinding the material entering the mill through the duct 12. Other mills may have other forms of screen supports.

A conventional hammermill screen, While arcuate in its overall configuration, is planar throughout its extent,

so that when its lateral edges are received in the grooves 24, it lies in the arcuate plans of said grooves and is lmll Patented Feb. 23, 1965 ICC thus separated from the rotor heads 21 by the radial distance between the grooves 24 and the outer circumference of the heads 21. In the grinding of various grains,

however it is desirable to vary the spacing between the' rotor heads 21 and the screen mounted in the mill grooves 24. It is also desirable to be able to change the grinding capacity of the mill by varying the distance between the rotor heads 21 and the screen carried in the grooves 24.

Our invention permits the adjustment of the distance between the rotor heads 21 andthe perforated section of the screen carried in the grooves 24. To this end, our screen comprises a generally rectangular arcuate section 26'having a plurality of openings 2'7 formed therein. A radially projecting imperforate web 28 extends around the periphery of the perforated section 26and is connected to an iinperforate border 3l? which projects laterally and longitudinally outwardly beyond the extent of the perforated lsection 26. As shown, the border 30 is also rectangular in form and lies in an arcuate plane offset from and parallel with the arcuate plane of the perforated section 26. Said border has an arcuate extent of about and the perforated section Y 26 has an arcuate extent slightly less than the arcuate extent of the border 30.

In the embodiment of our invention illustrated in the drawing, the lateral edges of the border 30 are inserted into the rnill housing grooves 24 until the screen is propJ erly oriented in the mill. With the perforated section 26 being disposed radially inwardly from the border 30, said perforated section will be disposed toward the rotor heads 21 out of the plane of the mill housing grooves 24, the amount of displacement of the perforated section 26 being a function of the radial extent of the web 28. It is to be understood, of course, that our invention also contemplates the perforated section 26 projecting radially outwardly from the border 30, in which event said perforated section would lie in a plane displaced farther away from the rotor heads 21 than the plane of the mill grooves 24.

We claim:

A screen for a hammerrnill, comprising an arcuate sheet of metal having a centrally disposed perforated section, an imperforate peripheral border extending laterally and longitudinally outwardly from said perforated section and radially offset out of the plane thereof, and a radially extending imperforate web interconnecting the outer edge of said perforated section and the inner edge of said border and retaining said perforated section and border in their offset relationship.

References Cited by the Examiner UNITED STATES PATENTS J. SPENCER OVERHOLSER, Primary Examiner. 

